The translation of basic biomedical knowledge to the development of effective therapeutic approaches depends on animal models that accurately reflect human diseases. Duchenne muscular dystrophy (DMD) is caused by a mutation in the dystrophin gene resulting in a non-functional protein. Currently, dystrophin-deficient mice and dogs are used to model this disease. Undoubtedly, these models have contributed substantially to our current understanding of DMD and development of therapeutic interventions, however, neither represents an ideal model as there are limitations to each. Consequently, there remains a critical need to continue to develop animal models that accurately reflect the DMD phenotype observed in humans. The objective of this application is the development and initial characterization of a porcine model of DMD that complements and extends currently available models. Our central hypothesis is that targeted disruption of the porcine dystrophin gene or genomic regulatory regions will result in transgenic swine that are dystrophin deficient and express a phenotype that is comparable to human disease progression. Our rationale for this hypothesis is that the pig is physiologically and phylogenetically more similar to humans than is either the dog or mouse. We will use homologous recombination to introduce targeted disruption of the dystrophin gene in somatic cells followed by somatic cell nuclear transfer to produce pigs with a dysfunctional dystrophin gene product due to an error in exon 46, a leading cause of human DMD. At the completion of this research project, we will have: 1) developed a porcine model of DMD using somatic cell nuclear transfer and 2) perform an initial molecular and physiological characterization of this porcine DMD model. This project is innovative because there is not a porcine model of DMD and because we will use somatic cell nuclear transfer, the only established method of knocking out a gene in large domesticated animals. Targeted disruption of specific exons will allow us to produce DMD pigs whose genetic mutation is tailored to the most prevalent genetic mutations in humans. We expect to produce a dystrophin deficient pig and perform an initial validation of this model for DMD research. Once validated, this pig and (or) tissue samples will be made readily available to researchers requesting them. Such a model will have a specific positive impact in that it will provide researchers with a much needed alternative and comparative model for DMD research. Further, given the physiological similarities between pigs and humans, they may prove to be an excellent standard for pre-clinical studies. This research will also enhance the efficacy and utility of somatic cell embryo transfer for development of biomedical models predicated on large animals. PUBLIC HEALTH RELEVANCE: Duchenne muscular dystrophy remains the most common, fatal, X-linked disease causing progressive muscle wasting, wheel chair confinement and ultimately, death. Though critical to the advancement of our current understanding of DMD and for pre-clinical investigations, existing mouse and dog models have limitations that necessitate the continued search and/or development of novel models of DMD. With the porcine model of DMD available, pre-clinical trials should be more predictive of human outcomes, as pigs are more closely related to humans than are either dogs or mice, and will improve efforts to streamline translational research.